1. Field of Invention
The invention relates to radio-controlled helicopters and more particularly to a model helicopter having a motor with a motor shaft being coaxial with a main shaft of a main rotor by epicyclic gearing so as to achieve a desired gear reduction ratio.
2. Description of Related Art
Major components of a drive mechanism of a typical type of model helicopter are shown in FIGS. 1 and 2 and comprise a motor (e.g., battery powered servo motor) 10, a small gear 12 fixed to a motor shaft of the motor 10, a main gear 11 in mesh with the small gear 12, a main shaft 1 fixed to the main gear 11, and a main rotor 13 at a top of the main shaft 1 and co-rotated therewith.
It is understood that the more powerful of the motor 10 the larger of the main gear 11 will be (i.e., greater diameter). One type of model helicopter having a main gear 11 with a diameter of 120 mm is available. However, greater diameter of main gear is not desired since it can adversely affect maneuverability, shorten the useful life of components, and greatly consume energy.
The invention is intended to obviate the above drawbacks by providing a model helicopter having a motor with a motor shaft being coaxial with a main shaft of a main rotor.